Without Spaces or punctiation - 30
Without Spaces - 31
With Space and no Punctuation - 37
With Space and no Punctuation if there is a space at the beginning - 38
With space and punctiation - 38
With Spaces and punctiation if there is a space at the beginning - 39
If you you mean the word letters then there is one.
If you mean literal tangible letters then there are none.